1. Field of the Invention
This invention relates to a method for using ethoxylated fatty amines as solution promoters or solubilizers in surfactant or detergent concentrates for detergent solutions, more especially in detergent concentrates for automatic bottle washing.
2. Statement of Related Art
In general, substances which are sparingly soluble or insoluble in water may be dissolved by adding solution promoters or solubilizers to the aqueous solutions. In many cases, the solution-promoting effect of additives such as these is based on the fact that the molecules of the substance added as solubilizer have a surfactant-like structure, i.e., a hydrophilic part and a hydrophobic part. In aqueous solutions, the solubilizer molecules form micelles in which the hydrophilic molecule ends are directed outwards to the water while the hydrophobic molecule ends are directed into the interior of the micelles. During solubilization, substances insoluble in the aqueous phase are incorporated in the interior of the micelles and are thus apparently dissolved in the aqueous phase. The quantity of solubilizer required to obtain a clear solution depends not only upon the quantity of substance to be dissolved, but also upon the solubilizing power of the solution promoter.
In the washing of beverage bottles, the various types of soil present in the bottle have to be removed to enable the bottle to be hygienically refilled. The keeping properties of the bottled beverage depend, inter alla, upon the complete removal of mechanical, biological or microbiological soil.
In addition, bottles are generally relabelled as part of the refilling process. Accordingly, not only external soil, but also labels and glue residues have to be completely removed to establish the proper conditions for labelling.
The washing of bottles intended for the beverage industry is often carried out using alkaline detergent solutions containing a plurality of components which (apart from relatively large quantities, for example 1 to 2%, of alkali metal hydroxides, more especially sodium hydroxide) contain other components, of which the quality and quantity are coordinated with the particular washing problem. At the present time, the detergent solutions are prepared in the corresponding bottle washing plants by addition of a detergent concentrate which contains all the necessary additives for problem-free washing to the plant water, and by subsequent addition of sodium hydroxide. However, in addition to readily water-soluble additives, such as inorganic salts and also inorganic and organic acids, most detergent concentrates also contain components sparingly soluble in water which, in the event of prolonged storage under adverse storage conditions, separate from the liquid detergent concentrates, thereby preventing the detergent from developing its full effectiveness in the in-use solutions. Components such as these are in particular the wetting agents and foam inhibitors present in the detergent concentrates, whose absence from the detergent solution results in defective operation of the washing plant and hence in unacceptable stoppages. Stoppages such as these frequently are caused by overfoaming of the bottle washing plant or even by labels which have not been removed. In order to keep these sparingly water-soluble detergent constituents in solutions, it has previously been standard practice to add to the detergent concentrates relatively large quantities of sodium cumene sulfonate which acts as a solution promoter and keeps even poorly soluble detergent components in solution. Although sodium cumene sulfonate enables the detergent concentrates to be stabilized, the use of this compound as a solution promoter has distinct disadvantages. On the one hand, the cost of detergent concentrates containing sodium cumene sulfonate is considerably increased by the high price of the solution promoter used in large quantities (In some cases detergent concentrates contain up to 25% of this compound), so that on economic grounds alone there is a need for a less expensive compound capable of acting as solution promoter. In addition, it is known that, particularly in the washing of beverage bottles, sodium cumene sulfonate as a detergent ingredient does not increase or assist the cleaning power of the prior art solutions. Accordingly, its sole function is to keep other poorly soluble components present in the detergent concentrates stably dissolved in the aqueous solution.
In addition, lower, generally branched alcohols, for example isopropanol, are known as solution promoters from the prior art. However, the disadvantage of isopropanol is that its handling involves special safety measures because isopropanol is not only readily inflammable, it also has a low flash point. In addition, its effect as a solution promoter is distinctly poorer than that of sodium cumene sulfonate.